Use of statistical representations of traffic flow in a data processing system

Abstract

An apparatus and method are provided for performing verification tests for a design of a data processing system. The apparatus comprises a system under verification representing at least part of the design of the data processing system, and a transactor for connecting to an interface of the system under verification, and for generating signals for input to the system under verification via the interface during performance of the verification tests. Profile storage stores a profile providing a statistical representation of desired traffic flow at the interface, the statistical representation providing statistical information for a plurality of traffic attributes and also identifying at least one dependency between such traffic attributes. The transactor then references the profile in order to determine the signals to be generated, such that the signals generated take account of the specified dependencies identified in the profile. Such a mechanism enables the transactor to more realistically replicate the traffic flow that will be observed in the real system. Another aspect to the present invention provides a mechanism for generating such profiles.

We claim: 
     
       1. An apparatus for performing verification tests on a system under verification representing at least part of the design of a data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a transactor for connecting to an interface of the system under verification, and for generating signals for input to the system under verification via said interface during performance of said verification tests; 
 profile storage for storing a profile providing a statistical representation of desired traffic flow at said interface, the statistical representation providing statistical information for a plurality of traffic attributes and identifying at least one dependency between traffic attributes in said plurality; and 
 the transactor referencing said profile in order to determine the signals to be generated, such that the signals generated take account of said at least one dependency identified in the profile, wherein said profile employs a hierarchical structure to identify said at least one dependency within said statistical representation of desired traffic flow. 
 
     
     
       2. An apparatus as claimed in  claim 1 , wherein said hierarchical structure is a hierarchical structure of histograms, each histogram providing statistical information for one of said traffic attributes. 
     
     
       3. An apparatus as claimed in  claim 1 , wherein the desired traffic flow is representative of a traffic flow that would be expected to be observed at said interface if the transactor were replaced with a functional model or an actual component of the data processing system. 
     
     
       4. An apparatus as claimed in  claim 3 , wherein said statistical representation of desired traffic flow is obtained by monitoring traffic flow occurring when said functional model or said actual component is used. 
     
     
       5. An apparatus for performing verification tests on a system under verification representing at least part of the design of a data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a transactor for connecting to an interface of the system under verification, and for generating signals for input to the system under verification via said interface during performance of said verification tests; 
 profile storage for storing a profile providing a statistical representation of desired traffic flow at said interface, the statistical representation providing statistical information for a plurality of traffic attributes and identifying at least one dependency between traffic attributes in said plurality; and 
 the transactor referencing said profile in order to determine the signals to be generated, such that the signals generated take account of said at least one dependency identified in the profile, wherein said traffic flow is produced in accordance with a transaction protocol and said plurality of traffic attributes comprise at least one transaction protocol attribute. 
 
     
     
       6. An apparatus for performing verification tests on a system under verification representing at least part of the design of a data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a transactor for connecting to an interface of the system under verification, and for generating signals for input to the system under verification via said interface during performance of said verification tests; 
 profile storage for storing a profile providing a statistical representation of desired traffic flow at said interface, the statistical representation providing statistical information for a plurality of traffic attributes and identifying at least one dependency between traffic attributes in said plurality; and 
 the transactor referencing said profile in order to determine the signals to be generated, such that the signals generated take account of said at least one dependency identified in the profile, wherein said traffic flow is produced in accordance with a transaction protocol and said plurality of traffic attributes comprise at least one timing attribute identifying timing between particular traffic signals produced in accordance with said transaction protocol. 
 
     
     
       7. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface; and 
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality, wherein said control input takes the form of a profile template setting out the plurality of traffic attributes and said at least one dependency, and the monitor produces said profile by populating the profile template based on the observed traffic flow. 
 
     
     
       8. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface; and 
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality, wherein said control input takes the form of an initial profile setting out the plurality of traffic attributes and said at least one dependency, and at least partially populated with statistical information, and the monitor produces said profile by supplementing the statistical information in the initial profile based on the observed traffic flow. 
 
     
     
       9. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface;
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality; and 
 comparison logic for comparing the profile produced by the monitor with an additional profile generated for an alternative representation of the data processing system, the additional profile also providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality. 
 
 
     
     
       10. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface;
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality; 
 
 an alternative system under verification representing at least part of the design of the data processing system, the alternative system under verification being a different implementation of the data processing system to the system under verification; 
 the monitor connecting to an equivalent interface within said alternative system under verification, and observing the traffic flow at that equivalent interface in order to produce an additional profile; and 
 comparison logic for comparing the profile and said additional profile in order to determine differences between operation of the system under verification and the alternative system under verification. 
 
     
     
       11. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface;
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality; and 
 error detection circuitry for coupling to an interface in an additional system under verification representing at least part of the design of the data processing system in order to observe the traffic flow at that interface, the error detection circuitry having access to the profile produced by the monitor and generating an error signal when the traffic flow observed is unexpected having regard to the profile. 
 
 
     
     
       12. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface; and 
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality, wherein said profile employs a hierarchical structure to identify said at least one dependency within said statistical representation of traffic flow. 
 
     
     
       13. An apparatus as claimed in  claim 12 , wherein said hierarchical structure is a hierarchical structure of histograms, each histogram providing statistical information for one of said traffic attributes. 
     
     
       14. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface; and 
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality, wherein said traffic flow is produced in accordance with a transaction protocol and said plurality of traffic attributes comprise at least one transaction protocol attribute. 
 
     
     
       15. An apparatus for generating a profile providing a statistical representation of traffic flow within a data processing system, said apparatus using a system under verification representing at least part of the design of the data processing system, the apparatus implemented on a general purpose computer, said apparatus comprising:
 a monitor for connecting to an interface of the system under verification, and for observing the traffic flow at that interface; and 
 the monitor being responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality, wherein said traffic flow is produced in accordance with a transaction protocol and said plurality of traffic attributes comprise at least one timing attribute identifying timing between particular traffic signals produced in accordance with said transaction protocol. 
 
     
     
       16. A method of performing verification tests for a system under verification representing at least part of the design of a data processing system, the method comprising the steps of:
 connecting a transactor to an interface of the system under verification; 
 during performance of said verification tests, inputting to the system under verification, via said interface, signals generated by the transactor; 
 storing within profile storage a profile providing a statistical representation of desired traffic flow at said interface, the statistical representation providing statistical information for a plurality of traffic attributes and identifying at least one dependency between traffic attributes in said plurality; and 
 causing the transactor to reference said profile in order to determine the signals to be generated for input to the system under verification, such that the signals generated take account of said at least one dependency identified in the profile, wherein said traffic flow is produced in accordance with a transaction protocol and said plurality of traffic attributes comprise at least one transaction protocol attribute, wherein said method steps are implemented on a general purpose computer. 
 
     
     
       17. A computer program product comprising a non-transitory computer readable storage medium storing a computer program which when executed on a computer causes the computer to perform the method of  claim 16 . 
     
     
       18. A method of generating a profile providing a statistical representation of traffic flow within a data processing system, said method using a system under verification representing at least part of the design of a data processing system, the method comprising the steps of:
 connecting a monitor to an interface of the system under verification; 
 observing, via the monitor, the traffic flow at that interface; and 
 responsive to a control input specifying a plurality of traffic attributes and at least one dependency between traffic attributes in said plurality, causing the monitor to produce said profile based on the observed traffic flow, the statistical representation of said profile providing statistical information for said plurality of traffic attributes and identifying said at least one dependency between traffic attributes in said plurality, wherein said traffic flow is produced in accordance with a transaction protocol and said plurality of traffic attributes comprise at least one transaction protocol attribute, wherein said method steps are implemented on a general purpose computer. 
 
     
     
       19. A computer program product comprising a non-transitory computer readable storage medium storing a computer program which when executed on a computer causes the computer to perform the method of  claim 18 .